qcom-charger: software fix for OTG soft-start

OTG devices with high capacitance could cause a system UVLO
due to a large amount of in-rush current drawn from battery.
Fix this by regulating the OTG boost start and altering PFM
threshold in software.

CRs-Fixed: 1048244
Change-Id: I08838d81eb99a424a3fd396582c56b120cbb46cb
Signed-off-by: Harry Yang <harryy@codeaurora.org>